Is Your Medicine Cabinet Making You Fat?

You've been watching your diet and following your usual exercise routine. But your pants seem a little tight and, sure enough, the scale shows that you've gained five pounds in the past month.

What's going on?

This may be hard to swallow, but a medication your doctor prescribed could be to blame. Certain prescription drugs used to treat mood disorders, seizures, migraines, diabetes, and even high blood pressure can cause weight gain - sometimes 10 pounds a month. Some steroids, hormone replacement therapy, and oral contraceptives can also cause unwanted pounds to creep up on you.

But even if you suspect a prescription medication is causing weight gain, never stop taking the drug without consulting your doctor, experts stress.

"Stopping some of these medications on your own can have very serious consequences," says Louis Aronne, MD, director of the Comprehensive Weight Control Program in New York City and president of the North American Association for the Study of Obesity. "It has to be done very carefully."

Madelyn H. Fernstrom, PhD, director of the Weight Management Center at the University of Pittsburgh Medical Center, agrees. Even if a medication causes weight gain, "an extra 10 pounds may be worth the trade-off of what that medication is doing for your overall health," she says.

Common Offenders That Can Cause Weight Gain

While no one knows exactly how many prescription drugs can cause weight gain, experts estimate the list includes more than 50 common medications.

Steroids such as prednisone, older antidepressants such as Elavil and Tofranil, and second-generation antipsychotics like Zyprexa are the biggest -- and most recognized -- promoters of weight gain, Fernstrom says.

Some other common offenders, says Fernstrom, include the antidepressants Paxil and Zoloft, the antiseizure medication Depakote, diabetes drugs like Diabeta and Diabinese, and the high blood pressure drugs Cardura and Inderal. Heartburn drugs like Nexium and Prevacid may also cause drug-induced weight gain.

Fernstrom tells WebMD that the medication-associated weight gain can be modest -- or as much as 30 pounds over several months.

"And in some cases, it is unrelated to the action of the drug itself," she adds. "For example, if an antidepressant makes people feel better, their appetite may be restored and they eat more."

Making matters more complicated is that some drugs, like Prevacid and Nexium, can cause weight gain in some people and weight loss in others.

"Not all drugs have the same side effects for all people," she says. "You have to work with your doctor to find the drug that's right for you."